Ban or moderate users from specific countries when registering using Maxmind's GeoLite2 Database
I also block ASN ranges for data centres where spambots register from at the Cloudflare level - although you do need to be careful because some legit bots may come from those same locations.
Please do at all cost avoid to give any information or feedback to the hints you already got that might help giving more than the most generic advice...
Use the forum search in this forum here? There have been dozens of threads with hints. One of them are the spaminator add ons - work brilliantly agains bot registrations (but not against human spammers that register manually):
This bundle will give you all three of the Spaminator addons. If you were to purchase these individually it would cost $120. But with this bundle you get all three for $100 a savings of $20...