Below are a series of questions to help you think through what might be some steps forward for your people; not all of them may apply.
Are they meeting to discover information?
If people are gathering to find things out then create ways that information can be publicly and constantly available. The more regular particular information is being sought, the more important it is to have it immediately available without request. Default to being open, not closed.
Are they meeting to provide upwards updates?
Providing upwards updates - i.e. pursuing the insight or blessing of a superior - can become a significant waste of time. Not just in the meeting but around it: think of all those hours people put into creating perfect powerpoints no one but a colleague or two will see, even if they're at the top. It's because these meetings are not just about seeking input, they’re about seeking job security. So they're an emotional burden as well as a time one. Managers should be part of getting the work done or a relationship should be created where they are approached as a consultant with advice to give. Manager input under normal circumstances is not by default “good advice”: it is often far too subjective, lacks sufficient insight into the problem and frequently is too late into the process to be of merit.
Are they meeting to gain buy-in?
You should, by default, see the need for approval or buy-in as a problem. Not all meetings in pursuit of them are an issue, but every time one happens you should be asking why it’s happening and if it’s really necessary. Is it really not possible to delegate decision making? The default response should be delegation. Do employees feel insecure in their roles if they are seeking buy-in for things?
Are they meeting for one to ones?
This is related to the point above as one to ones are a particular area to watch out for. Sometimes, employees see these formats as their best chance of managing the politics of a project or furthering the interests they personally feel are most pressing. They also use them like this if they’re not in a scenario capable of managing conflict well enough, so the manager must be dragged into it. In the normal course of business, centrally managed one to ones would be lower down my list of priorities. That's not to say they're a bad idea but other ideas are better (such as small groups for support), leaders just picking up the phone to see how people are and people being able to choose their own mentors if they want one - many of whom are probably best sourced outside of the organisation.
Are they meeting because togetherness is entirely an add on activity?
You need to be building a sense of togetherness and connection in the rhythm of normal meetings and discussions. If all meetings are entirely functional (e.g. you go straight to agenda items with no informal conversation) then people will start to crave additional connection time and go looking for more of it elsewhere.
Are they meeting because they’re obliged to?
Could you make meetings run on invitation rather than obligation? Most - if not all - meetings should have an element of choice. If they’re not interested in being there then there’s little point having them in the conversation. If they’re regularly not willing to show up then you can start to look at why that is.
Are they meeting because new activities are being created for them?
Employees don’t need hours of new activities imposed (by obligation) on them just because they’re not in the office with employees. This time is a gift for reflection, rest and a time to process: intense as it may be. See time not doing work as time connecting with themselves. They don't have to be "on the clock" to be pursuing personal mastery or finding joy. These sorts of activities can emerge from HR’s well-intentioned desire to keep employees happy and motivated but HR should not hold itself accountable to a standard of perfection that includes total, uninterrupted happiness. Nor is it responsible for people's motivation. Quirky activities to "make work fun" will begin to become tiresome if they're not naturally emerging.
Are they willing to take a meeting reset?
In places where meetings have become out of control - perhaps most of someone’s week is meeting rather than doing - then consider hitting the rest button. Ban all meetings for a fortnight. Take stock of what meetings were actually necessary or were missed on a personal level. Then start to think about what to introduce that is different or reintroduce things that were there previously; hopefully less of the latter. You may even want to consider making this meeting reset a regular occurrence as a check and balance against sliding back into it.