I've never encountered this spam detection problem in this forum at all. One thing I note is that the forum seems to be allowing both of you to write comparatively short posts. A speculative guess would be that there is a time limit being applied for how long a post takes to be submitted. The main defence against spambots is the "Captcha" feature (which stands for "Completely Automated Public Turing Test To Tell Computers and Humans Apart"), the code of letters and numbers which the spambot supposedly cannot read. It may be that spambots take an excessively long time to get through the Captcha feature (which they're not supposed to be able to get through), so posts that take a fairly long time to submit are seen as being suspect.
My practice in writing forum posts has been (since the 1990s) to compose the post offline using the Notepad text editor, and then copy and paste the text into the entry box for the forum post. I established that habit because you had to pay telephone connection charges in the UK to the internet by the minute back in the 1990s. So my posts in this forum are a bit longer than average, but they're submitted pretty quickly. If you're not doing it already, I would suggest writing posts offline and copying and pasting the text to see if that helps.
But I never type directly into a box. I always compose in Word then copy and paste; mainly because I was an early sufferer from the form of arthritis known as Heberden’s nodes, which inducees frequent errors.
When writing in Word and copying to paste onto the web, I always suggest that an interim stop be made, NOTEPAD. Paste you content in NOTEPAD and then reselect and paste into the text area on the website.
Lots of people have tried to wrangle the output of Microsoft into submission. It isn't easy.
Pasting into NOTEPAD, correcting any typos that you see there, and then continuing on has a nearly 100% success rate at avoiding underlying wickedness.
Someone might suggest that ignoring Word completely and just typing your draft in Notepad would be easier...