Once the type of message is set as html, next messages from this contact are displayed in html.
Once the message is viewed as html,
next messages from this contact are displayed in plain text with 10 miles long ascii raw html
There is no style stored for contacts. For each message it’s display style is determined separately, without any dependency on previous messages.
The problem in the screenshot should be solved by reducing the limit on the number of characters. Currently constant DC_DESIRED_TEXT_LEN in the core is 29000 characters, which is way too large.
that is definitly not html in your screenshot, it’s long links converted to markdown
DC should also not convert links to markdown, but simply show the link text without URL, if the URL is available in “Show full message” anyway. Email URLs are usually unreadable anyway because of huge tracking identifiers embedded in.
The limit is reduced to 5000 chars since core version 1.60.0.