If the fish is not laboring to swim, it's fine. If you don't see the fish swimming around his territory, or is hiding in a low flow area of the tank, that would be an indication that your flow is too high.Is this flow too strong for my Betta? The filter is small, but there are a lot of bubbles in the water from the filter. I took a video of it to show the filter flow.
What percentage of the tank would you say is high movement? What percentage is relatively still or low movement? Mostly low-move with a bit of active water can be fun for a Betta. Someone on here wrote recently that his Betta loves to dash through the bubbles like a kid in the sprinklers, and I too have found that mine, with mostly no movement, occasionally like to go for an action-packed moment of jumping over the bubbler.