Yes, the presence of water and certain appliances can significantly degrade the signal from a 5G repeater[2][6][8].
**Water: Water is particularly good at absorbing radio waves, especially at frequencies near 2.4 GHz, which is commonly used in Wi-Fi[2]. Water's attributes, including its mass and reflective nature, can obstruct and distort radio frequency signals[2]. Large bodies of water, such as aquariums or water-based heating systems, can impede Wi-Fi signals[8]. Atmospheric water vapor can also cause signal reduction, with heavy rain impacting weaker signals[4].
**Appliances: Appliances, especially those constructed with metal sheeting like refrigerators, can reflect Wi-Fi signals[6]. More significantly, appliances that emit radio waves in the same spectrum as Wi-Fi, such as microwave ovens operating at 2.4 GHz, can cause interference[6]. The placement of a Wi-Fi router near appliances may lead to signal degradation[6].
Citations:
[1] https://www.7signal.com/news/blog/indoor-cell-phone-signal-booster-destroys-5ghz-band
[2] https://superuser.com/questions/289913/why-if-i-put-wireless-access-point-near-water-fish-tank-will-degrade-its-signa
[3] https://www.microwavejournal.com/articles/38666-optimizing-active-repeater-architectures-for-distributed-5g-networks
[4] https://www.pagerpower.com/news/5g-strength-and-interference/
[5] https://www.123.net/blog/understanding-the-loss-of-signal-a-comprehensive-guide/
[6] https://choice.community/t/can-a-fridge-and-other-appliances-block-my-wifi-signal/16520
[7] https://mysignalboosters.com/blog/what-are-the-causes-for-poor-mobile-signal-reception/
[8] https://eyenetworks.no/en/10-things-that-disturb-and-block-wi-fi-signals/
[9] https://www.wilsonpro.com/blog/top-5-surprising-things-that-block-your-cell-signal