When people read text, left-to-right, their brain's visual processing expects everything that has the same level of detail and texture of letters to be actual text that needs to be interpreted.
If the actual text ends and the continuing texture is an non-text background, and the brain tries to interpret that, confusion results.
Likewise, if the stream of detail branches into two, the person has to stop and figure out which is actual text.
The result is confusion and mild frustration that can be very distracting.
Proposed solution
Make message text have a safe default background (just adding one ### tag at the beginning of the message)
Could be achieved using the answers in this StackExchange post as a base and decreasing the saturation and lumosity a bit.
Rounding off the background using border-radius could also make the now-mandatory background feel like a smooth, cohesive thing.
Details
When people read text, left-to-right, their brain's visual processing expects everything that has the same level of detail and texture of letters to be actual text that needs to be interpreted. If the actual text ends and the continuing texture is an non-text background, and the brain tries to interpret that, confusion results. Likewise, if the stream of detail branches into two, the person has to stop and figure out which is actual text. The result is confusion and mild frustration that can be very distracting.
Proposed solution
Make message text have a safe default background (just adding one ### tag at the beginning of the message)
Could be achieved using the answers in this StackExchange post as a base and decreasing the saturation and lumosity a bit.
Rounding off the background using border-radius could also make the now-mandatory background feel like a smooth, cohesive thing.