I've noticed this in the last month/two - on my 2018 MBP as well - my Logitech MX keys/mouse will both randomly disconnect for 5 seconds and then pair back, this wasn't happening before.

I don't use bluetooth input devides so can't comment on those, but I too noticed regressions in the last month or so with regards to AirPods.

They changed the firmware so that it can "seamlessly" move between devices but 1) it's not seamless at all - I actually disabled the new behavior and 2) I'm pretty sure something else changed regarding Bluetooth because switching between devices manually is slower and less reliable than it used to be before, and I bet this change is also responsible for the issue with input devices that you're seeing.

When my iPhone 12 wakes it breaks the Bluetooth connection between my iMac and Beats earphones.

I thought I was losing my mind - I've been experiencing the exact same thing with the MX keys/mouse over the past few months, and no amount of fiddling or reinstalling has been able to fix it. My scroll wheel regularly gets "clogged up" too, becoming unresponsive for 5-10 seconds, then dumping out all of my buffered scroll data at once in a furious explosion of scrolling. It's quite frustrating, and I've been looking forward to a fresh install of Big Sur to hopefully flush out whatever gremlins have been gunking things up.

Happens with Apple standard keyboard and mouse too. Restarting the computer AND accessories fixes it.

Same... and then about every 2 weeks bluetooth just dies taking the whole OS with it.

are you using 2.4Ghz wifi? Bluetooth uses a similar range and it gets interfered. If you have 5Ghz wifi try it, it might solve your problem.

Same.-

Do you have any USB C accessories? There are a lot of issues with interference between these two. When I unplug my USB C disk I can use bluetooth across my whole flat, with USB C plugged in I can barely leave my table without running into issues.

Anecdotal: Before Catalina, I had constant BT issues with Logitech and Microsoft BT mice on my 2015 MBP.

After upgrading to Catalina ~10 months ago the MS mouse has been flawless in daily usage. I haven't gone back and tried my Logitech mice.

I still have this issue on my MBP'15 and it drives me nuts (I use a headset daily that uses USB):

https://www.reddit.com/r/apple/comments/anvufc/psa_2018_macs...

It's basically not completely reproducible and is random.

Still wack. If my iPhone or iPad is between my mouse+keyboard and my 2019 mbp, Bluetooth shot to hell. Moving devices even a foot away helps dramatically though I still have to turn my mouse on and off every time I return from sleep. Happens with Logitech Mx, Matias keyboard, keychron mechanical keyboard. Maddening.

At this point, my 2015 Macbook Pro basically doesn't have bluetooth at all. Performance upgrades is truly all I desire

I doubt they'll ever update firmware on these older models :(

Given [1] I really hope they do.

[1] https://github.com/seemoo-lab/internalblue

My 2018 Mac Mini got a firmware update before it could run the installer.

Having said that I've got a USB key which if I use it everything on Bluetooth stops working.