It's real.

Adding a period adds a sense of finality and emphasis, while ending your sentence without one means the tone is lighter. This is inherited from texting habits

https://theconversation.com/why-does-using-a-period-in-a-text-message-make-you-sound-insincere-or-angry-61792

https://www.sciencedirect.com/science/article/pii/S0747563217306192?casa_token=2GuEomfEzyMAAAAA:xnd6UeoYlKC8-DUZBhiC4hh5p3CZefiXL6FX3ku7yTixGEd6pQ_n5BORZ-iFZY_-zz7rP_ArsyY

https://www.sciencedirect.com/science/article/pii/S0747563215302181?casa_token=NC-Hjq5VqI8AAAAA:JKFpxaM-KHvzCSr9Iw0OJVUiMsDh3ecSAQpdnYoFGMfeTm-HakGAVXK3XhYQin6uGrmS-Q2XjX8

https://www.sciencedirect.com/science/article/pii/S089858982030108X?casa_token=L_bofonFo1QAAAAA:yqKmY7po0gXJdUxoBDv4Lw_TGMxb-oeBplHLSKxlZySiBb7Z8nIQmfmMYAB3mfl0SI37fYWY6Ho

https://www.sciencedirect.com/science/article/pii/S0747563215302181?casa_token=FBJrNZQnj-UAAAAA:afZ2QLPX4KeSvY7_LtQ2nfJJCY27fOGrxCpQXP_UegQW1TqSShC0cCVFNVw9ZXyQW51N0Ssoc4Q