Earlier quoted context omitted.
Odoo suffers from others issues though. Not sure if this is still the case, but the mix of inline Python 2 Flask + XML was basically tech debt-as-a-service. Also the very ugly death they gave OpenERP/Odoo on-premise.
It's Python 3, no Flask (but werkzeug) and XML templates. It works for hundred thkusand clients, and you can install Odoo on premise as you like. I'm 90% dedicated to that. So... explain the "tech debt" thing, as I don't get it. You don't need Rust or microservices for every use case. Don't be fooled by marketing style "old style technology" bias and set up an account. PostgreSQL with synchronous workers works perfec…
I used to run Odoo on-premise for a small company about 3-4 years ago. The upgrade path (with the OpenUpgrade fork) was awful, many features (that WYSIWYG editor, Odoo Studio?) were locked to the cloud version, and there was little to no documentation. IIRC we even had to drop it because the delay between on-prem updates & cloud updates was too high.
And there were mentions of Flask in the logs, so no it wasn't just Werkzeug (which is synonymous with Flask since its inception, anyways).
I do not have fond memories of editing invoice templates blindly.