Signals from other channels are picked up as noise, lowering your signal-to-noise ratio (SNR). In principle, it could be picked up as data, but will almost always fail some very basic checks (correct preamble, destination MAC address, ...).
The channel mapping is built so 802.11b channels have sufficient distance to not influence each other. With 802.11g, the transmission bandwidth is wider, but the channel mapping was retained for compatibility purposes.
Interfering transmissions cause information to be lost, which is generally corrected for by a retransmission, decreasing efficiency of the system.
If any access points using the g protocol are around, it is generally best if everyone uses channels 1, 6 and 11 exclusively, as this avoids interference between adjacent channels, leaving only conflicts on the same channel, which the protocol is built to avoid even between different networks.
I've been playing with ESP01 and ESP03 and the ceramic antenna beats the PCB antenna by far.
While doing throughput tests I could not get the ESP01 to reliably get more than 1mbps until I touched the antenna with my hand (getting 10mbps). With the same program on the ESP03 the rate was always 10mbps.
Also with ESP01 I get 20-90ms of RTT in my home WLAN and with ESP03 I get a steady 2-3ms.
Best Answer
You really should check out the ESP32 Hardware Design Guidelines, where they clearly show ideal and non-ideal positioning of a module like the WROOM on a carrier PCB:
But if you can't let the module's PCB antenna over-hang due to whatever constraints of your overall design requirements, then this guideline is the fall-back option:
The 'keep-out zone' is where you have no components, no copper (no tracks, no planes, nothing), nothing but bare PCB.
So no, any tracks (and other metals) near the WROOM's PCB-antenna will negatively impact wireless performance, and also have wifi/bluetooth signals coupling at point blank range to your other digital signals.
P.S. Perhaps in future hold off for a day or two before awarding a correct answer, until there are a few answers to choose from :-)