So is yours an utterly false claim.
It doesn't stop such as you repeating it.
Now if you read books such as " life of Anthony" anasthasius, whose ministry spanned Constantine ( anasthasius important in outing the Arian heresies) you discover nothing actually changed in doctrine from one end of Constantine to the other. Certainly not in the ways often claimed including yours.
The problem with those who want to change Christianity such as the reformationists , they have to pick a date to claim the " church apostasized" so they can misrepresent their modern manmade tradition of modified doctrines as a " return" to something that never was. Problem is none of the dates stack up , indeed the apostasy never actually happened , even though Constantine gets the blame!
For example - Take basics - You will look in vain for " sola scriptura" in early church up to Constantine, because " sola scriptura" never was! - but the introduction of it as a manmade tradition of the reformation , did then allow all to make up their own version of doctrine from Middle Ages onwards , and that IS the apostasy, by ditching authority, , that launched 1000 more schisms. Once authority is removed, all can claim scripture means what they like.
What Constantine did do is allow a persecuted Christianity to become more open , since it didn't have to hide underground from persecution.