My Ubiquiti setup (one LR and one lite) was done back in 2018, devices on the network is roughly the same in the past 5 years, only phones laptops changed due to upgrades. Since 2020/21 their firmware updates started dropping support of old device randomly, or support become worse (devices get disconnected frequently or full bar but not responsive). First was my Kindle 3G keyboard, then Fitbit Aria Scale, then quite a few smart switches/plugs. I literally scratched my head to understand the settings, but they just won’t connect to the Ubiquiti AP. I had to buy an Eero as backup and continuously migrate these older devices as they are unable to connect. Their most recent firmware update last week kicked my Sony TV off the network(bought in 2018), I have no idea what they are thinking and wasted 1 hour rebooting and blaming Sony, then found it connect to the Eero AP just fine.
After I completely wiped the site configuration and migrated to the "new way" of doing it (I wish I had taken notes, I don't play with it often) and ensuring each AP got a fresh configuration, things stopped being "Weird".
I especially had issues with various IoT style sensors (e.g. ESP32) falling off, my largest annoyance was water leak sensors.
I wish I had some more technical notes to hand you, but it was definitely worth the evening of my time to basically "turn it off and back on again" from scratch.
Depends on specific model. Qualcomm-based ones are still good.