is it safe to compress backups for databases with TDE enabled?
I've been reading about this for a long time, and it seems it's not safe to compress a backup when the database has TDE enabled.

You asked about safety so replying. Using backup compression with TDE is safe and I have been using it quite a lot. What doesn't works well, for version SQL Server 2014 and below is the backup compression mileage (the amount of compression) you would get for versions below SQL Server 2016 is not great, let me put that the backups are slightly compressed as compared to backup compression on non TDE enabled database. From the Docs which Andrew Sayer shared (Backup compression with TDE
Starting from SQL Server 2016

Starting with SQL Server 2016 (13.x), setting MAXTRANSFERSIZE larger than 65536 (64 KB) enables an optimized compression algorithm for Transparent Data Encryption (TDE) encrypted databases that first decrypts a page, compresses it, and then encrypts it again. If MAXTRANSFERSIZE is not specified, or if MAXTRANSFERSIZE = 65536 (64 KB) is used, backup compression with TDE encrypted databases directly compresses the encrypted pages, and may not yield good compression ratios.

Starting from SQL Server 2019

Starting with SQL Server 2019 (15.x) CU5, setting MAXTRANSFERSIZE is
no longer required to enable this optimized compression algorithm with
TDE. If the backup command is specified WITH COMPRESSION or the backup
compression default server configuration is set to 1, MAXTRANSFERSIZE
will automatically be increased to 128K to enable the optimized
algorithm


is anyone experiencing errors during restore with compressed backups for tde databases?

Show me the error, you must be restoring TDE enabled database without certificates. My best guess