Step 1: Find the Private DNS setting.had my mi9 a couple of yrs, never again, flipping ads do my swede in, even after turning them off in settings they still appear in xiaomi apps like file manager
Step 2: Select 'Private DNS provider hostname'
Step 3: Type 'dns.adguard.com' (without the quotes)
Enjoy ad free experience. (Not 100% sure if it works for the ads for those phones but it does for apps)