On syncing my CalDAV file with my calendar, it shows that my tasks are due on 1st January 1970 (unix time 0), which is naturally not the case. If I download my CalDAV file, it has nothing in there.
Logs:
2021-09-06T19:23:53.3398863+05:30: WEB ▶ ::1 PROPFIND 207 /dav/lists 184.5399ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.5767443+05:30: WEB ▶ ::1 PROPFIND 207 /dav/lists/3 178.2103ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.583754+05:30: WEB ▶ ::1 PROPFIND 207 /dav/lists/2 185.22ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.5906261+05:30: WEB ▶ ::1 PROPFIND 207 /dav/lists/1 201.6672ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.8080597+05:30: WEB ▶ ::1 OPTIONS 204 /api/v1/notifications?page=1 0s - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) vikunja-desktop/0.16.0-dev Chrome/89.0.4389.128 Electron/12.0.9 Safari/537.36
2021-09-06T19:23:53.8105899+05:30: WEB ▶ ::1 GET 200 /api/v1/notifications?page=1 497.8µs - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) vikunja-desktop/0.16.0-dev Chrome/89.0.4389.128 Electron/12.0.9 Safari/537.36
2021-09-06T19:23:53.8138538+05:30: WEB ▶ ::1 REPORT 207 /dav/lists/1 218.2287ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.8564717+05:30: WEB ▶ ::1 REPORT 207 /dav/lists/2 266.85ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:53.8704699+05:30: WEB ▶ ::1 REPORT 207 /dav/lists/3 288.7988ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:54.141735+05:30: WEB ▶ ::1 REPORT 207 /dav/lists/2 277.6693ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
2021-09-06T19:23:54.1603246+05:30: WEB ▶ ::1 REPORT 207 /dav/lists/3 281.9302ms - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.57 Safari/537.36
Related: #753 - CalDAV not working properly with iOS - api - Gitea ; Warnings in outlook caldav (addon)