Staying with One UI 6.1 ?

[Android Dude777]

I presently have a Galaxy A 15 5G phone, and I still have One UI 6.1 and Android 14. I have two questions:

--Is there any reason not to stay with this? I have read a number of stories about problems with upgrading to One UI 7 and 8.

--And if/when I decide to get a new phone some day, will having One UI 6.1 be a problem?

Thanks.