What I've read dosnt agree with that statement. they are just being more careful with how they are used. This is also a growing trend, Ukraine are being more smart with how their kit is being deployed and used, and also how it is reported on, they have paid dearly by over publicising, opsec and the press taking liberties with reporting. I would say they are just as effective, its just that TTP's are evolving.People discussing that they are pretty ineffective now in the war, at the start Russia had little air defence up but they soon worked out how to deal with them.
Don't really see any combat videos of them now, only used for video footage.