You can't expect that just because something being added to your credit report causes it to dip will mean it automatically rises by an equal amount when that item is expunged from the report. First and foremost is the assumption that nothing else changed in the meantime, and it also assumes you understand how the credit scoring models work (not meant as an insult, just the observation that most people don't know how the scoring models work in general).
"Pay to remove" certainly helps when resolving collections, but the upside improvement after a collection is removed is frequently much less than peoplpe think it should be, for a variety of reasons which have to do with how the bureaus score credit.
If your credit utilization rose from what it was before then that could cause a more shallow recovery of your score, and the same is true if you opened any new accounts or closed any older ones (affecting average age of accounts). Did you have any new inquiries, any late pays, changes in address or employment? All of these can have some impact on your score. Lastly, if you have what's referred to as a "thin file" score, meaning you don't have a great deal of history, ANY event in your credit profile will have significantly more effect than people with longer, more established credit histories.
Even though most of the mechanisms affecting your score are well known, there are others that aren't precisely because the agencies want to keep the proprietary nature of their scoring models from being gamed any more than possible.
Also keep in mind that if you're using services like CreditKarma or Credit Sesame, those scores are what are referred to "consumer education scores" and may not reflect the precise score of your file.
Finally, there are changes coming to the scoring models, allegedly early in 2022, which are going to have consequences to credit scores because they will use additional non-credit related factors in the scoring algos that might be a boost for people with less credit history.
