@Ricardus Probably is because of music rights and/or licensing issues. Happens all the time in the world of streaming and modern music rights getting more expensive.
I recall that the Married....With Children series (at least on Disney+ and syndications) had to use generic music because they couldn't get the full rights to the iconic Frank Sinatra theme Love and Marriage.
Same goes for the Evangelion TV series outside Japan with Sinatra's "Fly Me to the Moon".