I fixed your post by properly formatting your pasted code as required…
Most likely because the Wemos WiFi reception/transmission is not as good as on your phone… and your phone may very well be switching back and forth to it’s Cell connection without you being aware of it.
Not all WiFi devices/antennas are created equal.
BTW, this has nothing to do with Blynk itself… any other process that requires a consistent WiFi connection would suffer the same way if on a fringe edge of signal strength.
Possible solutions would be to move the router to a more centralised location in the house, add in a WiFi repeater, switch to a different type of Wemos D1 Mini (Pro) with the option for an external antenna, hold the Wemos above your head and wave it around…