Preview in Slack is not available for Trend Questions

After applying new Metabase version 0.41.2 previews became unavailable in Slack messages.
Can you please help me understand what's happened here and how we can resolve it? Thanks!

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Hi @martasakal
Which version did you upgrade from?
I think there's too much getting lost in translation, can you include a screenshot of what Trend questions looks like now and how they looked before?
Check the log for errors - Admin > Troubleshooting > Logs.

Here examples of questions with/without previews. I could not find any errors in logs

@martasakal If you want to show a graph like the bottom picture, then change the visualization to Line.

It's not the same type of visualization that we had before with trends.
Also numbers are not displayed as images. (For example in New Customers - By Week)

@martasakal I don't understand. Too much information is getting redacted. Have you included the visualization "New Customers - By Week" ?

Ok, let me show you some faked numbers.
How trends question preview was looking before:

And how it looks now:

@martasakal I cannot reproduce. I'm getting the same numbers for the same query using different visualization.
But Trend visualization will not show a graph anymore. If you want a graph, then change the visualization to a Line.

Ok, but if I click on image preview it shows other graph:


@martasakal Okay, I'm not sure what's going on there. Perhaps it's a Slack issue? Metabase does not control what Slack does.

Can I find POST request that Metabase sends to Slack anywhere?

@martasakal The Slack requests is handled in the integration:
We're working on redoing the entire Slack integration:

We experience the exact samt issue since upgrading to 0.41.2. Images are no longer posted to the metabase_files channel and the bot stopped listening to commands such as list or show. There are no errors in the log. I just upgraded to 0.21.3 and the problem is still there.

@sco01 Slack has in all their wisdom decided to deprecated some APIs with only two weeks notice, which made it impossible for anyone to implement fixes first.
Though, this should only be a problem for newly created Bots.
There isn't much we can do about this besides working on the full re-write of our Slack implementation.

I see. Yes. The problem we experience appeared on Novemer 16. The day we updated to 0.41.2. This was using an existing bot that has been in use since June this year, so not a newly created bot. I think a full rewrite is in order anyway since the current integration seems to use a legacy Custom Integration API that has been marked as deprecated since March 2017 according to the slack changelog.