I'm currently running the Hidden Shrine of Tamoachan and noticed a discrepancy between the official published adventure in it's current form on DDB and a stat block that exists in the Encounter Builder. 

Tloques-Popolocas (Area 7. The Sepulcher of Tloques-Poplocas)  does not have a stat block in Appendix B in either the physical or digital version of the adventure, but one exists here on DDB and it's not homebrew.  I'm unaware of any official errata (although the campaign could really use some) that added this stat block.

The stat block itself is serviceable, but it also has some problems.  The block lists his AC as 15 (from the vampire spawn stat block, I'm assuming), which likely does not factor in the bracers of defense that he may or may not be wearing based on what the party does as the tomb is uncovered.  This is also further confused by the fact that the adventure lists a ring of protection in the text (which would make it AC 18), but not in the listed treasure, so what his exact AC is is anybody's guess. 

Also, he has the innate ability to cast hold person which does not list an ability save DC for it.  

The stat block for Tloques-Popolocas is the vampire spawn with the permanent changes already pre-applied. These changes are:

• Modified shapechange ability
• Children of the Night action with appropriate changes
• The ability to innately cast hold person

Temporary effects such as those caused by his regeneration and the magic items he might be wearing aren't applied. Basically the team have taken the information presented by the book and done the work combining it for you, hence why the stat block exists on D&D Beyond and not in the book.

It should be noted that the adventure does not specify the DC for his innate hold person, hence why it's not presented in the stat block.

Hope this clarifies things.

Thanks.  I do appreciate your efforts on the stat block.  It saves me a lot of work not having to homebrew one.