My ISP is providing dynamic IP adresses but I want to be able to always use the same IP. I did some research and I ended up with the conclusion that it's not really possible to do from my side alone, is this really it? and if so why are services like PayPal suspending the access to one's account when their algorithms detect multiple IPs for the same account if dynamic IPs are a thing? Thanks a lot!
Your ISP is leasing an IP to your CPE(Modem/router etc). Most will charge if you want this to be static. Some its a monthly fee, some its a one time charge. Others do not offer it at all (Cellular providers can be among these).
IP blocking is a blunt tool but only some IPs are dynamic and their rate of change varies. Some are "sticky" and may only change once or twice a year, some change upon reconnection, some change nightly.
Paypal most likely blocked you because of simultaneous access from multiple IP's. This is suspicious for a personal or small business account as even if you were using a few devices they should be through the same connection and use a single address.