I ran into the same problem with Trezor Suite. Annoyingly, there was no way to make it generate more addresses beyond the gap limit.
The only workaround there is to send bitcoins (
just don't use dust) to your last address (
e.g. if using an unused new account: m/84'/0'/0'/0/19)
And it will let you generate another batch beyond that address.
But yeah, just use Electrum/Sparrow if generating 20 more unused address is a must.