In Wireshark, the packet bytes panes show the data of the current packet in which format?

Wireshark does not render packet bytes in decimal; decimal notation would be less compact and is not standard for byte-level packet analysis.

ASCII is presented as a secondary column next to the hex dump for printable characters only and is not the primary format of the Packet Bytes pane.

Binary representation is not used in the Packet Bytes pane because it would produce an extremely verbose and unreadable output for any non-trivial packet.

Wireshark displays packet payload data in the Packet Bytes pane as a hex dump - each byte is represented as a two-digit hexadecimal value - because hexadecimal is compact and maps cleanly to binary data. An ASCII column is shown alongside purely as a readability aid, but hexadecimal is the primary format of the pane.