Sign Data growing on "data merge" or "ctrl + pick block"

Doing the command "data merge" or "ctrl + pick block" creates extra text in the signs data.

Example fixing a typo on a sign:

276, 70, 237 has the following block data: {x: 276, Text4: "{\"text\":\"\"}", y: 70, Text3: "{\"text\":\"\"}", z: 237, Text2: "{\"text\":\"\"}", id: "minecraft:sign", Text1: "{\"text\":\"A cool siogn\"}"}

then running command:

/data merge block 276 70 237 {Text1:"{\"text\":\"A cool sign\"}"}

results in

276, 70, 237 has the following block data: {x: 276, Text4: "{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}", y: 70, Text3: "{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}", z: 237, Text2: "{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}", id: "minecraft:sign", Text1: "{\"extra\":[{\"text\":\"A cool sign\"}],\"text\":\"\"}"}

then to make a copy of the sign to place somewhere else using pick block results in this

276, 70, 237 has the following block data: {x: 276, Text4: "{\"extra\":[{\"text\":\"\"},{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}],\"text\":\"\"}", y: 70, Text3: "{\"extra\":[{\"text\":\"\"},{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}],\"text\":\"\"}", z: 237, Text2: "{\"extra\":[{\"text\":\"\"},{\"extra\":[{\"text\":\"\"}],\"text\":\"\"}],\"text\":\"\"}", id: "minecraft:sign", Text1: "{\"extra\":[{\"text\":\"\"},{\"extra\":[{\"text\":\"A cool sign\"}],\"text\":\"\"}],\"text\":\"\"}"}

And it will keep growing the more you "ctrl + pick block" or "data merge" the sign