Update 10/2021: I have since switched to Ferdi after all. Mostly because I suddenly had Rambox CE crash constantly all of a sudden. Plus development does not seem very active and there was some trouble using WhatsApp and others. Ferdi is serving me well at the moment.
Problem statement: I have lots of different (communication-related) apps that I use. And each has its own client. That is a true mess on my (Windows) computer.
Solution: A messaging browser. I have been using one of those before, but not in a while. So which is it going be? Rambox!
Why Rambox and not something else? Because Rambox supports a ton of services (tbh, the others do too), it has no limit on how many services I configure (Franz let me only configure 3 for free and I am not willing to pay EUR 2.99 month to get 6), it is actively developed (All-in-One Messenger‘s development seems to have stalled), and it is fast (Ferdi was slower). Oh and Rambox is cross-platform, too.
Which apps are we talking about? In my case we are mainly talking about WhatsApp, Threema Instagram (the full web client), Instagram Direct (the Insta messaging only), Pixelfed, Mastodon, Slack and Facebook Messenger.