google – Mobile usability warnings in Search Console after redirecting to new domain and design

I’ve just implemented a 301 redirect from a old (bad) website to a new domain with a new design. 1 day after the redirect I’m getting mobile usability errors in google search console. Errors like text to small to read, content wider than screen etc.

Previously I’ve had none of these errors so I’m wondering if this is expected behaviour or should I be worried?

Google rankings have also dropped slightly since I got these errors.