Cold wallet vs. Trade Republic

Ledger vs Trade Republic

Honest question: I already have my stuff on a ledger but am thinking of buying BTC now on Trade Republic. The last years I found it too uncomfortable to go through the hassle of sending them to an exchange to take profits. Missed out on some serious gains this way. Is there really any downside to just buying the BTC ETF via Trade Republic? I mean the funds are secured up to 100k €, and I am talking about way less to buy.
Would like honest feedback.
Cheers