This is the first variable star discovered in the TF15 field. It is the GPX-TF15A-808 (TYC 3967-3027-1 in Cygnus) a strange ROT star discovered during the GPX survey and submitted to VSX by P. Benni, A. Burdanov, F. Salvaggio, A. Marchini, R. Papini.
This system is also reported in a paper:
Variability Properties of Four Million Sources in the TESS Input Catalog
Observed with the Kilodegree Extremely Little Telescope Survey by Oelkers R. J. et al.
Magnitude variation goes from 11.94 to 12.01 V.
Epoch: HJD 2458377.684
Period: 0.87659 d
This is the link to VSX record: https://www.aavso.org/vsx/index.php?view=detail.top&oid=687319