RTL are going to unify their brand across all countries later in the year. I'm surprised they haven't done this earlier, it's a real hodgepodge of logos, including some really nasty ones. Their Dutch portfolio has a horrible range of totally different logos for each channel. I've always liked the German one though. I wonder if the new one will be inspired by any of the existing logos.
There never really was a need to have consistent logos in different countries before. The different RTL channels have always been entirely made for their respective markets, so the fact that they used different logos made little difference. RTL have historically been fairly utilitarian in their branding, using the RTL name to launch into new markets, reusing logos when suitable, but rarely imposing a corporate standard for the sake of having a corporate standard. Channel 5 would never have been renamed "RTL5", as speculated on this forum 15 years ago.
The major change now is that RTL appears to want to become a streaming company. If they want a streaming service that is common for its five markets, with the same appeal as Netflix, then I suppose a common RTL brand is needed.
One problem for RTL has always been that the synergies in owning major national broadcasters are limited. People in the Netherlands aren't magically interested in watching the Hungarian version version of Farmer Wants a Wife just because RTL happens to own channels in both countries. The operations in different countries have mostly been run independently and they haven't really bothered with making original content that appeals to people in many countries. For a unified RTL brand to make sense they would have to overcome that problem, but the press release doesn't really go into that.