@Alex Gagnon Thanks for your patience on this.
I have checked with the internal team, and they have confirmed that for P0v3 app service plan SKU also has the limit of 1,920 for Outbound IP connection per instance.
Also, I have relayed the same feedback to the content author team internally to update the documentation accordingly.
I hope the answer helps. Please let me know if you have any further queries.
Please accept as Yes if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues.