Some stale plugins are currently installed & some may not be vetted for the current version of OBS. Start with Advanced Scene Switcher.
That said, you have some Rendering Lag/GPU overload, system overload (Audio lagging) going on along with internet issues. To stop that Rendering Lag (which should clear up the encoding lag too), try running only your main monitor at high refresh rates & set the other @ 60HZ. Your CPU is powerful but running high refresh rates (180 & 240) on both monitors may be overloading it on a single thread, see link.
17:53:59.780: WriteN, RTMP send error 10060 (4097 bytes)
17:53:59.781: WriteN, RTMP send error 10038 (679 bytes)
17:53:59.781: WriteN, RTMP send error 10038 (42 bytes)
17:53:59.781: [rtmp stream: 'rtmp multitrack video'] Disconnected from rtmp://use20.contribute.live-video.net/app
17:53:59.781: Output 'rtmp multitrack video': stopping
17:53:59.781: Output 'rtmp multitrack video': Total frames output: 1590905 (1594151 attempted)
17:53:59.781: Output 'rtmp multitrack video': Total drawn frames: 392254 (398636 attempted)
17:53:59.781: Output 'rtmp multitrack video': Number of lagged frames due to rendering lag/stalls: 6382 (1.6%)
17:53:59.781: Output 'rtmp multitrack video': Number of dropped frames due to insufficient bandwidth/connection stalls: 3246 (0.2%)
17:53:59.781: Output 'rtmp multitrack video': Reconnecting in 2.00 seconds..
17:53:59.782: [rtmp stream: 'rtmp multitrack video'] Freeing 2865 remaining packets
17:53:59.782: Video stopped, number of skipped frames due to encoding lag: 6382/398598 (1.6%)
17:53:59.883: Video stopped, number of skipped frames due to encoding lag: 6382/398603 (1.6%)
17:53:59.969: Video stopped, number of skipped frames due to encoding lag: 6382/398608 (1.6%)
17:54:00.035: Video stopped, number of skipped frames due to encoding lag: 6382/398612 (1.6%)
17:54:00.091: Video stopped, number of skipped frames due to encoding lag: 6382/398615 (1.6%)
18:06:20.317: Source Desktop Audio audio is lagging (over by 520184.86 ms) at max audio buffering. Restarting source audio.
18:06:33.173: obs-streamelements-core: streaming stop requested by UI control
18:06:34.205: [rtmp stream: 'rtmp multitrack video'] User stopped the stream
18:06:34.205: [rtmp stream: 'rtmp multitrack video'] Socket send buffer is 4194304 bytes
18:06:34.205: Output 'rtmp multitrack video': stopping
18:06:34.205: Output 'rtmp multitrack video': Total frames output: 176390
18:06:34.205: Output 'rtmp multitrack video': Total drawn frames: 44105 (44205 attempted)
18:06:34.205: Output 'rtmp multitrack video': Number of lagged frames due to rendering lag/stalls: 100 (0.2%)
18:06:34.205: [rtmp stream: 'rtmp multitrack video'] Freeing 1 remaining packets
18:06:34.205: Video stopped, number of skipped frames due to encoding lag: 98/44159 (0.2%)
18:06:34.287: Video stopped, number of skipped frames due to encoding lag: 98/44163 (0.2%)
18:06:34.355: Video stopped, number of skipped frames due to encoding lag: 98/44167 (0.2%)
18:06:34.404: Video stopped, number of skipped frames due to encoding lag: 98/44170 (0.2%)
18:06:34.446: Video stopped, number of skipped frames due to encoding lag: 98/44173 (0.2%)
https://calculatebottleneck.com/guides/monitor-refresh-rate-guide
OBS Knowledge Base. Learn best practices to solve encoding performance issues
obsproject.com
OBS Knowledge Base. Dropped frames? Your stream is disconnecting? This guide will help you troubleshoot common connection issues.
obsproject.com